Alterations in metabolism and gap junction expression may determine the role of astrocytes as “good samaritans” or executioners

Our knowledge of astroglia and their physiological and pathophysiolo- gical role(s) in the central nervous system (CNS) has grown during the past decade, revealing a complex picture. It is becoming increasingly clear that glia play a signifi- cant role in the homeostasis and function of the CNS and that neurons should no longer be considered the only cell type that responds, both rapidly and slowly, to elec- trochemical activity. We discuss recent advances in the field with an emphasis on the impact of hypoxia and ischemia on astrocytic metabolism and the functional relation- ship between glucose metabolism and gap junctions in astrocytes. We also address the controversy over whether astrocytic gap junctions mediate protection or killing of neu- rons during or after hypoxic or ischemic insults. V C 2005 Wiley-Liss, Inc.